While there are some differences in the education systems in many countries in the world, education is __________.

Cultural exchange ______ better understanding betweenpeople in different countries

(2010·安徽)It was from only a few supplies that she had bought in the village ________ the hostess cooked such a nice dinner

The three sisters decided to hold a family party to ______ their parents gold wedding.

It is required that the students ________ mobile phones in their school, so seldom ________ them using one.[ ]